The present invention generally relates to a testing apparatus for the measurement of ions in fluids to be tested. More particularly, this invention pertains to a clinical testing apparatus for measuring the concentrations and amounts of various ions in body fluids to be tested. U.S. Pat. Nos. 3,941,565; 3,994,171; and 4,048,040 describe certain prior test methods and apparatus of the present invention.
The importance of the electrolyte concentrations in body fluids is becoming apparent. Electrolytes have a complex role in regards to the control of the physiological balance of the body. Therefore, it is important that numerous ionic concentrations and levels in body fluids be quickly and easily ascertainable not only in a hospital setting but a doctor's office or small clinic.
Often presently available testing apparatus have one or more of a number of drawbacks which were often accepted by their users. In brief, most of the presently available testing apparatus are of the flow-through type in which the sample to be tested is moved by some means past a sensor such as an electrode partly in order that the sensor be constantly washed with the sample thereby providing a more exact measurement. These devices are generally large and may contain very intricate and complex tubing systems connected with one or more pumps to move the fluid through the tubes. These devices in many instances require the formation of bubbles within the tubing to improve the mixing of the fluid to be tested around the sensor or electrode that is immersed or located within the tubing. The equipment is generally large, requires considerate maintenance, and in almost every instance, tests a diluted sample. Dilution of samples has the drawback of degrading the exactness of the reading or measurement being taken. There is at leasat one device presently available in which the flow-through principal is not used. In that device, a sample is conveyed to a spinning chamber having an electrode within it and the measurement is taken while the chamber is spinning. Then the chamber has to be washed out with a washing solution before the next test is taken. The sample used in this device is also a diluted sample. The devices that are presently available often have fixed electrodes and the sample is pumped through a sometimes complex tubing system to the electrode.